Friction plate and mating member

ABSTRACT

A friction plate member having teeth provided with a pressure angle different from that of the teeth of a mating member.

United States Patent Livezey 1 Aug. 1, 1972 [s41 FRICTION PLATE AND MATING [56] References Cited EMB R 72 I E G u I di F UNITED STATES PATENTS 1 anap 3,209,611 10/1965 Iyoi ..74/462 3,476,228 11/1969 Pritchard ..l92/107 R [73] Assignee: General Motors Corporation, 3,256,967 6/1966 Heid ..192/107 R Detroit, Mich. Primary Examiner-William F. ODea [22] 1970 Assistant Examiner-Randall Heald [211 App] 33,0 Attorney-W. E. Finken, A. M. Heiter and R. L. Phillips [52] US. Cl ..l92/l07 R, l92/70.2, 64/9, 57 ABSTRACT [51] Int Cl 74/462 zi zag 6 A friction plate member having teeth provided with a new s 64/9 pressure angle different from that of the teeth of a 188/218 XL; 74/462 mung member 4 Claims, 3 Drawing Figures PATENTEDAus 1 I972 3.680575 Zzyf azd fizw ATTORNE Y FRICTION PLATE AND MATING MEMBER This invention relates to a friction plate and mating member and more particularly to the pressure angles of the teeth of a friction plate and mating member.

The invention is illustrated in aclutch subassembly having a clutch plate with internal involute-teeth mating with the external involute teeth of a rotary hub. The clutch plate'teeth have a'pressureangle larger than that of the rotary hub teeth to prevent tip loading of the plate teeth and thereby lessen the probability of plate breakage.

An object of the present invention is to provide a new and improved combination of friction plate and mating member.

Another object is to provide connection between a friction plate member and a torque transmitting member by mating teeth having different pressure angles.

Another object is'to provide tooth shapes on a friction plate member and a torque transmitting member that prevent tip loading of the plate teeth.

These and other objects of the inventionwill become more apparent from the following description and drawing in which:

FIG. 1 is a partial view of a clutch subassembly having tooth structure according to the present invention.

FIG. 2 is an enlarged view taken on the line 2-2 in FIG. I.

FIG. 3 is a view taken on the line 3-3 in FIG. 2.

Referring to FIGS. 1 and 2, the invention is illustrated in a clutch subassembly comprising an annular metal clutch plate or member having internal circumferentially spaced involute teeth 12 engaging or mating with external circumferentiallyspaced involute teeth 14 of a metal rotary hub l6.-Friction discs l8 'of suitable material are bonded to the opposite sides of plate 10 to provide the desired frictional characteristics on contact with sandwiching friction plates (not shown) of the complete clutchassembly. The toothed cluteh'plate is piloted on the teeth 14 whichare elongated in the axial direction to permit sufl'icientaxial movement of the clutch plate for the engagement.

As best shown in FIG. 3, the hub teeth 14 have an involute shape developed from a base circle whose radius is indicated as R The clutch plate teeth '12 also have an involute shape which is developed from a base circle whose radius is smaller than that of the hub teeth 14 and is indicated as R; that is, R is les than R The minor radius of the plate teeth 12 is indicated'as R, and the major radius of these teeth is indicated as R,,. Both the plate teeth 12 and hub teeth 14 have the same pitch circle whose radius is indicated as R and since the base radius R of the plate teeth 12 is less than the base radius R of the hub teeth 14, the pressure angle of the plate teeth 12 is larger than the pressure angled of the hub teeth 14.

Since the plate teeth 12 have a largerpremure angle than'the hub teeth 14, there is effected a divergence 20 between the involute sides 21 and 22 of the mating teeth 12 and 14, respectively, this divergence being exaggerated in FIG. 3 to clearly illustrate this feature. By providing the divergence 20, the tip 24 onthe engagement side of each plate tooth I2 is prevented from contacting the dedendum portion of the side 22 of each hub tooth l4 and instead, initial contact occurs between the tip 26 of each hub tooth l4 and the dedendum portion of the side 2l--of each plate tooth 12. Thus tip loading of the'plate teeth is prevented and as a result, the probability of plate breakage is lessened. Furthermore,'the divergence is made sufficiently smallso that normal tooth wear will provide custom fitting of the profiles of the mating teeth .thereby minimizing the efiect of tooth spacing errors with more teeth coming intocontact until the tooth bearing areas approach proportions such that wear ceases.

To illustrate the extent of the exaggeration of the divergence20 and also to provide an example of an actual .structure constructed according'to the present invention, the objective of preventing clutch plate tip loading while providing automaticcustom fitting of the profiles of the teeth will be met by providing the hub teeth '14 with a 30 pressure angle and the clutch plate teeth .12 with a 31 pressure angle. It will be appreciated thatthissubstantial difierence in pressure angles may be efiected by providing the hub teeth with a standard pressure angle and increasing the pressure angle of theplate teeth over standard and also by having the pressure angle of clutch'plate teeth remain standard and decreasing the-pressure angle of the hub teeth below-standard. Furthermore, :both the clutch plate teeth and the hub teethmay have nonstandard pressure angles to'provide thedivergence. It will be further understood that while the invention has been illustrated for use in a clutch assembly, the invention isalso applicable to brake assemblies wherein braking operation tions of the teeth of said one memberareprevented from coming into contact with the dedendum portions of the teeth of the other member while the dedendum portions of the teeth 'of said one member are permitted to continuously contact the tip portions of the teeth of the other member.

2. In combination, a friction plate member, a torque transmitting member, circurnferentially spaced teeth having a geometric form on said torque transmitting member, circurnferentially. spaced teeth on said friction plate member mating with and having the same geometric form as the teeth on said torque transmitting member, the teeth of each member having a tip portion and a dedendum portion, and the teeth on said friction plate member having a pressure angle substantially larger than that of the teeth on said torque transmitting member so that the tip portions of the teeth of the friction plate member are prevented from coming into contact with and being loaded by the dedendum portions to continuously contact teeth of the torque transmitting member while the dedendum portions of the teeth of said "friction plate member are permitted to .continuously contact the tip portions of the teeth of the torque transmitting member.

while the dedendum portions of the teeth of the friction plate member are permitted tov continuously contact the tip portions of the teeth of the rotary member.

4. In combination, a friction plate member having internal circumferentially spaced involute teeth, a'rotary member having external circumferentially spaced involute teeth' for continuously mating with the teeth on said friction plate member, the teeth of each member having a tip'portion and a dedendum portion, and the teeth on said friction plate member having a pressure angle substantially larger. than that of the teeth on said rotary member so that the tip portions of the teeth of the friction plate member are prevented from contacting the dedendum portions of the teeth of the rotary member while the dedendum portions of the teeth of said friction plate member are permitted to contact the tip portions of the teeth of said rotary member.

g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,680,675 Dated August 1, 1972 lnventorrls) William G. Livezey It is certified. that error appears in the above-identified patent and that said 'Letters Patent are hereby corrected as shown below:

Column 2, Line 62,- "to continuously contact" should read of I Column 4, Line 12, insert continuously after "to" and I before "Contact" Signed and sealed this 2nd day of January 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. I ROBERT GOTTSCHALK Commissioner of Patents Attesting' Officer 

1. In combination, a friction plate member having circumferentially spaced teeth, a torque transmitting member having circumferentially spaced teeth mating with the teeth on said friction plate member, the teeth of each member having a tip portion and a dedendum portion, and the teeth on one of said members having a pressure angle substantially different from that of the teeth on the other of said members so that the tip portions of the teeth of said one member are prevented from coming into contact with the dedendum portions of the teeth of the other member while the dedendum portions of the teeth of said one member are permitted to continuously contact the tip portions of the teeth of the other member.
 2. In combination, a friction plate member, a torque transmitting member, circumferentially spaced teeth having a geometric form on said torque transmitting member, circumferentially spaced teeth on said friction plate member mating with and having the same geometric form as the teeth on said torque transmitting member, the teeth of each member having a tip portion and a dedendum portion, and the teeth on said friction plate member having a pressure angle substantially larger than that of the teeth on said torque transmitting member so that the tip portions of the teeth of the friction plate member are prevented from coming into contact with and being loaded by the dedendum portions to continuously contact teeth of the torque transmitting member while the dedendum portions of the teeth of said friction plate member are permitted to continuously contact the tip portions of the teeth of the torque transmitting member.
 3. In combination, a friction plate member having circumferentially spaced involute teeth, a rotary member having circumferentially spaced involute teeth mating with the teeth on said friction plate member, the teeth of each member having a tip portion and a dedendum portion, and the teeth on said friction plate member having a pressure angle substantially larger than that of the teeth on said rotary member so that the tip portions of the teeth of the friction plate member are prevented from coming into contact with the dedendum portiOns of the teeth of the rotary member while the dedendum portions of the teeth of the friction plate member are permitted to continuously contact the tip portions of the teeth of the rotary member.
 4. In combination, a friction plate member having internal circumferentially spaced involute teeth, a rotary member having external circumferentially spaced involute teeth for continuously mating with the teeth on said friction plate member, the teeth of each member having a tip portion and a dedendum portion, and the teeth on said friction plate member having a pressure angle substantially larger than that of the teeth on said rotary member so that the tip portions of the teeth of the friction plate member are prevented from contacting the dedendum portions of the teeth of the rotary member while the dedendum portions of the teeth of said friction plate member are permitted to contact the tip portions of the teeth of said rotary member. 